The full name of this pachycephalosaur, or bone-headed dinosaur, is Dracorex hogwartsia (pronounced DRAY-co-rex hog-WART-see-ah), which is Greek for Dragon King of Hogwarts), and as you might have guessed, there's a story behind this. After it was excavated in 2004, in South Dakota's Hell Creek formation, the partial skull of this dinosaur was donated to the world-renowned Children's Museum of Indianapolis, which invited visiting kids to name it as a promotional stunt. Considering the other possibilities, the allusion to the Harry Potter books (Draco Malfoy is Harry Potter's ill-mannered nemesis, and Hogwarts is the school they both attend) doesn't seem quite so bad!
The Complication of the Species
There's a significant amount of controversy about Dracorex among paleontologists, some of whom think this is really a species of the very similar-looking Stygimoloch (whose much less child-friendly name means "horned demon from the river of hell.") The latest news: a research team headed by Jack Horner has concluded that both Dracorex and Stygimoloch represented early growth stages of yet another dinosaur genus, Pachycephalosaurus, though this conclusion hasn't yet been accepted by everyone in the scientific community. What this means is that, as Pachycephalosaurus juveniles grew, their head ornamentation became more and more elaborate, so adults looked very different from teenagers (and teenagers looked very different from hatchlings). What it also means, sadly, is that there may be no such dinosaur as Dracorex hogwartsia! A few things that thescientifice community does agree on is that the Dracorex existed in the woodlands of what is modern-day North America during the late Cretaceous period (70-65 million years ago) eating a diet of primary plants and growing to be about 12 feet in length and 500 pounds.
However it winds up being classified, Dracorex (or Stygimoloch, or Pachycephalosaurus) was a classic pachycephalosaur, equipped with an unusually thick, ornamented, vaguely demonic-looking skull. Males of this slender, two-legged dinosaur probably head-butted each other for dominance within the herd (not to mention the right to pair up with females during mating season), though it's also possible that Dracorex's massive head served to intimidate predators, by butting away the flanks of curious raptors or tyrannosaurs.